Known as a technique for processing an analog signal is one which generates a ramp signal by a ramp signal generation circuit and compares the analog signal with the ramp signal as a reference signal, so as to process the analog signal. For example, the following Patent Literature 1 discloses a technique for AD-converting analog signals outputted from respective pixels in the field of CMOS (Complementary Metal Oxide Semiconductor) image sensors. Counting with a clock signal is started simultaneously with supplying a comparator with a ramp-shaped reference voltage. When an analog signal inputted from a pixel having a light-receiving element equals the reference voltage, the counting action is stopped, and the count value at this point of time is latched as pixel data. This makes it possible to output a digital signal corresponding to the analog signal. Non Patent Literatures 1 and 2 also disclose similar techniques.